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Training can modify back muscle response to sudden trunk loading


Sudden, unexpected loading to the trunk has been reported in the literature as a potential cause of low-back disorders. This study’s aim was to investigate the effect of “readiness training” on the response to sudden back loading among untrained healthy individuals. The study included 19 participants and 19 matched controls. All were employees at the National Institute of Occupational Health. The participants received ten 45-min training sessions during a 4-week period. The training focused on reactions to a variety of expected and unexpected sudden trunk loadings, including balance and coordination exercises. Before and after the training, all subjects were tested for reaction to sudden trunk loading (SL). This entailed applying a horizontal force of 58 N to the subject’s upper back. Elapsed time—measured between SL and stopping—decreased significantly in the training group (from 337 to 311 ms) compared with the control group. The improved stopping time was associated with a changed EMG signal, characterized by an increase in the early parts of the response (up to 225 ms) and a subsequent decrease. EMG onset latency was unaffected by training. This study is apparently one of the first to demonstrate that the response to sudden trunk loading can be improved in healthy subjects without an increase in pre-activation and associated trunk stiffness. In perspective, the results indicate a possibility for a training-induced reduction of the risk of low-back injuries, e.g., in nurses exposed to sudden trunk perturbations during patient handling.

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  1. Cohen J (1969) Statistical power analysis for the behavioral sciences. 2nd edn. Academic Press, New York

  2. Hodges PW, Bui BH (1996) A comparison of computer-based methods for the determination of onset of muscle contraction using electromyography. Electroencephalogr Clin Neurophysiol 101(6):511–519

    CAS  PubMed  Google Scholar 

  3. Latash ML (1998) Neurophysiological basis of movement. Human Kinetics. Champaign, Illinois

  4. Lavender SA, Marras WS, Miller RA (1993) The development of response strategies in preparation for sudden loading to the torso. Spine 18(14):2097–2105

    CAS  PubMed  Google Scholar 

  5. Lavender SA, Shakeel K, Andersson GBJ, Thomas JS (2000) Effects of a lifting belt on spine moments and muscle recruitments after unexpected sudden loading. Spine 25(12): 1569–1578

    Article  CAS  PubMed  Google Scholar 

  6. Magnusson ML, Aleksiev A, Wilder DG, Pope MH, Spratt K, Lee SH, Goel VK, Weinstein JN (1996) Unexpected load and asymmetric posture as etiologic factors in low back pain. Eur Spine J 5:23–35

    CAS  PubMed  Google Scholar 

  7. Mortimer JA, Eisenberg P, Palmer SS (1987) Premovement silence in agonist muscles preceding maximum efforts. Exp Neurol 98(3):542–554

    CAS  PubMed  Google Scholar 

  8. Mortimer JA, Webster DD (1983) Dissociated changes of short- and long-latency myotatic responses prior to a brisk voluntary movement in normals, in karate experts, and in Parkinsonian patients. Adv Neurol 39:541–554

    CAS  PubMed  Google Scholar 

  9. Nielsen J, Crone C, Hultborn H (1993) H-reflexes are smaller in dancers from the Royal Danish Ballet than in well-trained athletes. Eur. J Appl Physiol Occup Physiol 66(2):116–121

    CAS  Google Scholar 

  10. Owen BD (1986) Personal characteristics important to back injury. Rehabil Nurs 11(4):12–16

    CAS  PubMed  Google Scholar 

  11. Pope MH, Aleksiev A, Panagiotacopulos ND, Lee JS, Wilder DG, Friesen K, Stielau W, Goel VK (2000) Evaluation of low back muscle surface EMG signals using wavelets. Clin Biomech (Bristol, Avon) 15(8):567–573

    Google Scholar 

  12. Radebold A, Cholewicki J, Panjabi MM, Patel TC (2000) Muscle response pattern to sudden trunk loading in healthy individuals and in patients with chronic low back pain. Spine 25(8):947–954

    CAS  PubMed  Google Scholar 

  13. Skotte JH, Fallentin N, Pedersen MT, Essendrop M, Strøyer J, Schibye B (2002) A new set-up for studying sudden loading of the low back. J Biomechanics (submitted)

  14. Smedley J, Egger P, Cooper C, Coggon D (1995) Manual handling activities and risk of low back pain in nurses. Occup Environ Med 52:160–163

    CAS  PubMed  Google Scholar 

  15. Tani T, Yamamoto H, Ichimiya M, Kimura J (1997) Reflexes evoked in human erector spinae muscles by tapping during voluntary activity. Electroencephalogr Clin Neurophysiol 105:194–200

    CAS  PubMed  Google Scholar 

  16. Thomas JR, Salazar W, Landers DM (1991) What is missing in p less than .05? Effect size. Res Q Exerc Sport 62(3):344–348

    CAS  PubMed  Google Scholar 

  17. van Dieen JH, Thissen CE, van de Ven AJ, Toussaint HM (1991) The electro-mechanical delay of the erector spinae muscle: influence of rate of force development, fatigue and electrode location. Eur J Appl Physiol Occup Physiol 63(3–4):216–222

    Google Scholar 

  18. Wilder DG, Aleksiev AR, Magnusson ML, Pope MH, Spratt KF, Goel VK (1996) Muscular response to sudden load. Spine 21(22):2628–2639

    CAS  PubMed  Google Scholar 

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Correspondence to Mogens Theisen Pedersen.

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Pedersen, M.T., Essendrop, M., Skotte, J.H. et al. Training can modify back muscle response to sudden trunk loading. Eur Spine J 13, 548–552 (2004).

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  • Exercise
  • Low-back pain
  • Biomechanics
  • Electromyography